Proposals have been made to produce regenerated cellulose fibre by spinning a solution of cellulose in a suitable solvent. An example of such a process is described in UK Patent Specification 2043525, the contents of which are incorporated herein by way of reference. In such a solvent spinning process, cellulose is dissolved in a solvent such as a tertiary amine N-oxide, e.g. N-methylmorpholine N-oxide, which is a solvent for the cellulose. The solution is then spun through a suitable die to produce filaments, which are washed in water to remove the solvent. The fibres may be stretched during the processing, both before and after washing as required. Typically, the fibre is then treated with a finish before being utilised in a known manner.
The present invention is particularly concerned with the treatment of such solvent-spun cellulose fibre so as to reduce the tendency of the fibre to fibrillate. Fibrillation is the breaking up in a longitudinal mode of the fibre to form a hairy structure. A practical process to reduce fibrillation needs not only to reduce fibrillation itself, but also to have a minimal effect on subsequent dyeability of the fibre and to have as little effect as possible on tenacity and extensibility of the fibre. Processes have been investigated which will reduce fibrillation but these unfortunately reduce the tenacity and the extensibility of the fibre. Other processes have been investigated which, while not reducing tenacity and extensibility, have a deleterious effect on the dyeability of the fibre.
The present invention addresses the need for a process which not only reduces fibrillation tendency but also yields a treated fibre which has a significantly reduced tendency to fibrillate without significant reduction in tenacity and extensibility and without significant deleterious effect on dyeability. Maintaining a balance between all of the required properties of the fibre is extremely difficult because it is not sufficient to produce a fibre with a low tendency to fibrillation but which has a very low tenacity or a very low extensibility or a very poor dyeability. It would also be unsatisfactory to produce a fibre which was so rigid as to be unworkable or so embrittled as to be unprocessable.